Solve the following

Question

1. Josh money is twice that of Justin. Sheena's money is twice that of Josh money. If Justin's money is $30, what is the average amount of each has?

2. Sonny got grades 89,89 and 87 ins science language and Reading, respectively what must be his grade in math to get the average grade of 90 in all subjects.

3. The average age of 5 students is 12 years old.a student with age of 10 drops out. Find the new average of the remaining 4 students.

Answer 1

I whink the answer is Josh = 2(Just); Sh = 2(Josh); Just = $30

Josh = 2(30) = $60; Sh = 2(60) = $120

(30 + 60 + 120)/3 = 210/3 = $70 average

2) This one (and #3) are "reverse avg" problems where the avg is a given value. If avg = total/no. of items,

then total = avg * no. of items.

Target of 90 for 4 tests means the total has to be 360. With the existing 3 tests, the total is 265. Therefore, the math test must be 360 - 265, or 95.

Check: (89 + 89 + 87+ 95)/4 = 360/4 = 90 avg.

3) Avg age 12 * 5 students = total of 60. One student, aged 10, drops out out. New total is 50 for remaining 4 students. Avg. age now is 50/4 = 12.5 yrs

Answer 2

1) Josh = 2(Just); Sh = 2(Josh); Just = $30

Josh = 2(30) = $60; Sh = 2(60) = $120

(30 + 60 + 120)/3 = 210/3 = $70 average

2) This one (and #3) are "reverse avg" problems where the avg is a given value. If avg = total/no. of items,

then total = avg * no. of items.

Target of 90 for 4 tests means the total has to be 360. With the existing 3 tests, the total is 265. Therefore, the math test must be 360 - 265, or 95.

Check: (89 + 89 + 87+ 95)/4 = 360/4 = 90 avg.

3) Avg age 12 * 5 students = total of 60. One student, aged 10, drops out out. New total is 50 for remaining 4 students. Avg. age now is 50/4 = 12.5 yrs